The tennis ball is one of three possible tools to remove the mud in Cutter's Cave, along with the spatula and the brush. The boat varnish is an alternative jar to give Gladys to test the strength of the female suspects.

Thank you! Recognizing that our audience consists of many players not used to adventure games, and who still wanted to play an Agatha Christie game, I began by trying to give players hints to puzzles in several different ways:

1. Hints buried in the dialogue and actions of characters for those who play the game as a story. (My way!)

2. Hints in the Notebook for those who like to play the game as an adventure game.

3. A really obvious way to keep them from wandering, and er point them in the right direction...?

Once I had the finger, I then decided to make the finger's mechanism a puzzle as well, so that the players had something to solve in Poirot's office. They can still use it, of course, even if they don't know its secret.